HV battery testing before purchase

Not an easy thing to do safely. A 220 volt incandescent light bulb " preferably at leased a 100 watts" connected as a load and the voltage monitored will give an indication of it's condition. A 100 watt bulb will give a discharge of around 0.5 amps. It should hold the voltage steady for some while providing the battery has a charge above 201.5 volts. Bearing in mind the dangerous nature of high voltage particularly when it's DC, hardly something you can do in a breakers yard.

John (Britprius)

 

Paying that sort of money I would want a minimum of 1 month guarantee in writing, but preferably 3 months. If the battery is working when you put it in the chances are it will be ok. The VCI with Techstream will check the battery once installed.
It has to be your decision. Even with reconditioned batteries there is always the risk the company may go out of operation before your guarantee expires.

John (Britprius)

 

Can you link me to Art's information. For a battery in good condition all the module pair voltages should be close "within a couple of tenths of a volt" also all the resistances should be within a couple of thousandths of an ohm.

With Techstream you can monitor the voltages "record" while in reverse with the wheels chocked and gently applying the accelerator to load the HV battery. If you have an EV switch as in the EU Prius you can do this in drive. You can look at the recording later to see any deviation in battery voltage, temperature rise in one area, and extra resistance increase in any module pair.

John (Britprius)

 

Just checked out Art's page, and he basically uses the test using the graph feature rather than the numerical list outlined in my post above. Large variations in voltage between module pairs particularly under load is the give away.

John (Britprius)

 

I would look for packs that were recently removed from a working vehicle and the measure the resting voltage (should give some idea to the health of the battery). Would also help to buy from vehicles which have been used in cooler climates (ie less chance of heat damage) and with lower mileage. Beyond that you would need to have it installed and use Techstream (mini VCI) to view the battery stats in operation.